Simple Distillation Residue Curves for a Mixture of Pentane and Dichloromethane at 750 mmHg
The vapor-liquid equilibrium behavior of the binary mixture composed of pentane and dichloromethane at 750 mmHg can be represented by the following empirical equation:[more]
, where and .
This mixture exhibits a minimum boiling azeotrope at approximately 52.08% pentane mole fraction.
The simple distillation residue curve is given by the following implicit relation:
where is the warped time, is the pentane mole fraction in the still at , and is the initial pentane composition in the still. The warped time is related to clock time by , where is the vapor rate from the still in mole/s and is the liquid hold-up in the still in moles.
If the initial composition is , the azeotropic composition, then .5208 ∀ ξ. Indeed, this mixture forms a positive azeotrope at 52.08% pentane mole fraction.
If the initial composition in the still is rich in pentane (i.e., ), then the only component that is left in the still at large values of the warped time is pentane (i.e., as ).
If the initial composition in the still is rich in dichloromethane (i.e. ), then the only component that is left in the still at large values of the warped time is dichloromethane (i.e., as ).[less]
For more information, see:
M. F. Doherty and M. F. Malone, Conceptual Design of Distillation Systems, New York: McGraw-Hill, 2001.